Refrigerator



J. L. KNIGHT REFRIGERATOR April 19', 1938.

Filed Sept. 5, 1935 Invent-(5r James l Knight,

8 A9 is Attorneg.

Patented Apr. 19; 1938 UNITED STATES PATENT OFFICE 1 Claim. (61. 62-89)My invention relates to refrigerators and more particularly to anarrangement for regulating the circulation of cooling air in the foodstorage compartments thereof.

5 Many types of refrigerators, and particularly those designed forhousehold use, include a. single heat insulated food storage compartmentin which a large variety of articles-are stored; The food storagecompartment is ordinarily cooled by a cooling unit such as a refrigerantevaporator which may be supplied with liquid vaporizable refrigerantfrom a compressor-condenser unit.

a Trays of water, or the like, to be frozen are sup-' ported on suitablecooling surfaces of the evaporator and articles such as raw meat whichare best preserved at temperatures below 32 F. are also supportedthereon. Other articles, such as bottles of milk, are stored on suitableshelves located in the remainder of the food storage compartment 20which is preferably maintained at a temperature of about 45 F. It isalso frequently desirable to preserve vegetables and similar articles inthe food storage compartment, which are subject to rapid deteriorationdue to dehydration. The rate 25 of dehydration of such articles is afunction of the quantity of air circulated thereover when the humidityof the air is comparatively low. Further difficulties have beenencountered in maintaining the desired temperature and humidityconditions within such a food storage compartmentbecause of thecomparatively large changes in ambient temperature to which the exteriorsurfaces of the compartment are subjected.

35 It is an object of my invention to provide a refrigerator havingaheat insulated food storage compartment and an improved arrangement forregulating the circulation of air therein in order to maintain thedesired temperature and humidity 40 conditions in different portionsthereof suitable for the preservation of various articles storedtherein.

Further objects and advantages of my inven-' tion of a portion of therefrigerator shown in Fig. 1.

Referring tothe drawing, Ihave shown in Fig. 1 a refrigeratordesign'edfor'household use provided with a cabinet. having a rectangularopen-top 5' sheet metal shell l0 provided with a rectangular door'opening I I in the front wall thereof. A ree tangular open-topsheet'metal inner liner l2 arranged in spaced relation within the outershell [0 forms a food storage compartment l3 within 16 the cabinet. Thefrontwall of the inner liner I2 is. provided with a rectangular dooropening ll therein which registers with the somewhat larger door openingI l in the outer shell lll the adjacent edges thereof being securedtogether by a strip of non-hygroscopic 'heat insulating material [5. Thedoor opening thus formed in the front wall of the food storagecompartment I3 is closed by a suitable heat insulated door l6 which issupported by hinges arranged at the side of the door 20 opening. Thecabinet-is supported on a series of sheet metallegs H.

The food storage compartment i3 is cooled by a refrigerating machinesupportedona removable heat insulated top wall Illa/of; the cabinet.The, refrigerating machine illustrated includes a U-shaped refrigerantevaporator l8jof thesheet metal type which'i's supported on the'lowerside of the removable-top wall Illa. vaporized liquid refrigerant issupplied to the evaporator l8 from a compressor-condenser unit mountedon the upper surface of the removable top wall ma. Gaseous refrigerantis compressed by a motor driven compressor located in a hermeticallysealed casing I9 and is supplied to a cylindrical natural draftair-cooled condenser 2|] which extendsabout the casing IS. Thecompressed refrigerant circulating through passages 2| of the condenser.20 is cooled by air circulatinglupwardly over the surfaces of thecondenser dueto natural draft and is 40 liquefied thereby; This liquidrefrigerant'is supplied to the evaporator l8 through a suitableregulating valve (not shown) and the liquid refrigerant circulatingthrough the evaporator l8 is'vaporized by the absorption ofheat fromarticles supported on the surfaces of the evaporator and from the aircirculating in thefood storage compartment l3. The refrigerant thusvaporized in the evaporator I8' is returnedto the motor drivencompressor in the casing is and the cycle is repeated and continueduntil the temperature within the food storage compartment l3 isloweredto the desiredvaluer In the illustrative form of my invention freezingtrays 22 are supported on the lower portion of the g5 evaporator I8 andice cubes are frozen therein. The evaporator I8 is also provided with anintermediate shelf 23 on which freezing trays, meat or similar articlesmay be supported, which it is desirable to maintain at a temperaturebelow 32 F. A series of reticulated shelves 24 of wire work constructionwhich permit a free circulation of air therethrough are supported inspaced relation within the food storage compartment I3 and articles tobe preserved such as bottles of milk and dishes of food may be placedthereon.

A shelf is arranged in the food storage compartment, the major portionof the surface of which is imperforate, and an arrangement is providedwhich cooperates with this shelf, to regulate the quantity of aircirculated vertically between the upper portion of the food storagecompartment above this shelf and the lower portion of the food storagecompartment below this shelf. In the illustrative form of my inventionan imperforate removable rectangular horizontal sheet metal shelf 25 issupported in the food storage compartment I3 on a series of horizontalstuds 26 secured to the side walls of the inner liner I2. The rear andside edges of the sheet metal shelf 25 are arranged in close abuttingrelation to the rear and side walls of the food storage compartment I 3in order to prevent the circulation of air therebetween. The front edgeof the shelf 25 is arranged in spaced relation with respect to the innerwall of the door I6 to define a vertical air passage disposed betweenthe front edge of the shelf and the door and communicating between theupper and the lower portions of the food storage compartment. Arectangular sheet metal shutter 21 extends along the front edge of theshelf 25 and is pivotally supported on a rod 28 the opposite ends ofwhich are journaled in suitable holes provided in the side walls ofinner liner I2. The rear edge of the shutter 21 is bent over the rod 28and is rigidly secured thereto so as to prevent relative displacement ofthe rod 28 and shutter 21. The ends of the rod 28 are tightly fitted inthe holes of the side wall of the inner liner I2 in order that theshutter 21 will remain in any particular position to which it isrotated. The shutter 21 is provided with an .index pointer 29 which isrigidly secured thereto and the angular position of the shutter 27 isthus indicated by the index pointer 29 and a series of suitable indexmarks 30 formed on the adjacent portion of the side wall of the innerliner I2. The shutter 21 is of sufficient width that it extends entirelyacross the space between the front edge of the shelf 25 and the innerwall of the door I6 when rotated to a horizontal position in alinementwith the shelf 25 and cooperates with the shelf 25 and the door I6 toregulate the circulation of air in the food storage compartment I3. Itwill be noted that the front edge 25a of the shelf 25 is folded over inorder to provide a smooth edge in abutting relation with the rear edgeof the shutter 21 so as to prevent the leakage of air therebetween. Theshelf 25 and the shutter 21 are preferably covered with a coating ofvitreous enamel or similar material in order that they shall presentsmooth easily cleaned surfaces.

In the operation of the refrigerator described above the evaporator I8is preferably maintained at a temperature above 0 F. andbelow 32 R, anaverage temperature of about 20 F. being desirable. The air within thefood storage corrpartment I3 surrounding the evaporator I8 is ooledthereby and since its specific gravity is cred upon the lowering of thetemperature thereof, it circulates downwardly into the lower portion ofthe food storage compartment I3 while the warmer and hence lighter airin the lower portion of the food storage compartment is displaced andmoves upwardly to a position adjacent the evaporator I8 where it is inturn cooled. The air within the food storage is thus circulated thereindue to the convection currents set up as described above. The air withinthe food storage compartment I3 is maintained at an average temperatureat about 45 F. Vegetables or other articles which are subject to rapiddeterioration due to dehydration are supported in a removablereticulated receptacle or basket 3| of wire work construction below theimperforate shelf 25. Since the dehydration of such articles is afunction of the quantity of air circulated thereover when the humidityof the air is low, it is desirable that the quantity of air circulatedover the articles contained in the basket 3| be limited to a minimumamount compatible with the maintenance of the temperature necessary fortheir proper preservation. The humidity of the air within the foodstorage compartment I3 is usually comparatively low since the surfacesof the evaporator I8 are maintained at a temperature susbtantially belowthe average temperature of the air and as,a consequence the moisture inthe air within the food storage compartment is rapidly condensed on thesurfaces of the evaporator. By means of the shutter and shelfarrangement which I have provided, the quantity of air circulatedbetween the upper portion of the food storage compartment above theshelf 25 and the lower portion of the food storage compartment I3 belowthe shelf 25 may be regulated in order to limit the amount of aircirculated through the lower portion of the compartment to the minimumamount required in order to maintain the articles in the basket 3| atthe desired temperature. These articles may be maintained at atemperature slightly. higher than that prevailing in the upper part ofthe food storage compartment, that is at a temperature of approximatelyR, if desired. The transfer of heat from the lower portion of the foodstorage compartment to the upper portion thereof with a minimumcirculation of air is also facilitated by the particular shelfconstruction which I have provided since the shelf 25 is made of metaland has a relatively high heat conductivity. The position of the shutter21 may be varied in accordance with the temperature of the air outsidethe cabinet. During the hot summer months when the outside temperatureis high and hence the heat leakage to the interior of the cabinet ishigh, the shutter 21 may be rotated downwardly to a vertical position inwhich the maximum amount of circulation of air between the upper andlower portions of the food storage compartment I3 is provided. Duringthe cold winter months the temperature outside the cabinet is relativelylow and, as a consequence, a comparatively small amount of heat leaksinto the interior of the cabinet. Consequently, the shutter 21 may berotated to a horizontal position or to a position in which only a smallamount of circulation of air is permitted. It will thus be seen that Ihave provided an arrangement in which a minimum amount of cooling air iscirculated through the lower portion of the food storage compartment inorder that the relative humidity in the lower portion of the foodstorage compartment is maintained at a maximum value and hence thedehydration of articles stored therein is minimized. While I have showna particular embodiment of my invention in connection with a householdtype refrigerator, I do not desire my invention to be limited to aparticular construction shown and described and I intend in the appendedclaim to cover all modifications within the spirit and scope of myinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:--

A refrigerator provided with a heat insulated food storage compartmenthaving bottom and top and side walls and having a door opening in thefront wall thereof, a heat insulated door for closing said door opening,means including a refrigerant evaporator located in the upper portion ofsaid food storage compartment for cooling said food storage compartmentand for circulating air therein, an imperforate horizontal sheet metalshelf extending across said food storage compartment above the bottomwall thereof and below said evaporator, said shelf having at least threeedges thereof arranged in close abutting relation to said sidewalls ofsaid food storage compartment and dividing said food storage compartmentinto upper and lower portions accessible through said door opening, thefront edge of said shelf being arranged in spaced relation with respectto said door to define a vertical air passage disposed between the frontedge of said shelf and said door and communicating between the upper andthe lower portions of said food storage compartment, and means includinga shutter pivotally supported between said front edge of said shelf andsaid door and cooperating with said shelf and said door for regulatingthe quantity of air circulating vertically through said air passage andbetween the upper portion of said food stor-.

